Heat transfer device



Oct. 28, 1952 DAQIDSON 2,615,686

HEAT TRANSFER DEViCE Filed Kay 29, 1948 IN V EN TOR.

Amy-mews) Patented Oct. 28, 1952 HEAT TRANSFER DEVICE John Davidson, Evansville, Ind., "assignor to Servel, Inc., New York, N. Y., a corporation of Delaware Application May 29, 1948, Serial No. 30,025

1 This invention relates to heat transfer devices such as, for example, an absorber of an absorption refrigeration system and more particularly to improvements in liquid distributing apparatus of the type in which liquid drips successively from one to another of a plurality of generally horizontal elements arranged one over the other in an enclosure.

One form of such a liquid distributing appa-,

ratus is illustrated and described in United States Letters Patent to Per Edberg No. 2,399,916 issued May 7, 1946, and entitled Refrigeration. The liquid distributing apparatus illustrated in said patent comprises pipe sections arranged one over the other so that liquid supplied to the top section drips from each section to the next lowermost section. It has also been proposed to pro.- vide similar elements with circumferential ridges arranged in spaced relation along their length which are preferably formed by the loops of a wire coiled helically on their periphery. The wire loops on the periphery of the elements break up any rivulets of liquid flowing therealong and provide a series of drop formers at spaced points along the bottom.

It is the object of my invention to improve the liquid distribution and drop forming characteristics of such wires and to facilitate themanufacture and assembly of the liquid distributing apparatus. I accomplish this object by forming the wire loops, preferably in the form of a helical coil, into a, cylinder having a greater inside diam- 1 Claim. (Cl. 257-35) eter than the outside diameter of the pipe sec- 7 tions so that the wires may be easily and quickly applied by merely sliding them over the ends of the pipe sections. When helical wire coils are so mounted on the pipe sections the loops are spaced from the sides and bottoms of the pipe sections. With such an arrangement the cohesion of the liquid in the space between the wire and pipe section produces a desirable wiping action of the liquid on the pipe section as it tends to follow the helical pathof the individual loops of the wire coil. The spacing of the wire coils from the periphery of the pipe sections also produces smaller drops which fall onto and flow over the surface of the next lowermost pipe sections without splashing when they hit the top thereof.

The foregoing and other objectsof the invention and details of construction are more fully views. The drawing is for the purpose of illustration only and is not a definition of the invention, reference being had for this purpose to the appended claim. In the drawing:

Fig. 1 is a sectional view of the absorber of an absorption refrigeration apparatus and showing the liquid distributing means of the present in-, vention applied thereto;

Fig. 2 is an enlarged view of a portion. of one of the vertical cooling coils in the absorber show. ing the helically coiled wires forming spaced ridges on the periphery of the pipe sections;

Fig. 3 is a further enlarged view of a portion of one of the pipe sections and showing the loose arrangement of the helically coiled wire on a pipe section to provide spaces between the bottom of the pipe and the individual turns of the wire coil;

and

Fig. 4 is a transverse sectional view taken on line 4-4 of Fig. 3.

In the drawing, the heat transfer device to. which the present invention is shown applied. is the absorber of an absorption refrigeration, system such as illustrated and described in said; United States Letters Patent to Per Edberg re-- ferred to above. For further description of such: a refrigeration system reference is made to the: Edberg application which may be considered as incorporated herein. Suflice it to state that the absorber comprises an hermetically sealed casing- 5, preferably of cylindrical shape, having spaced ducts 6 at its top for connection to an evaporator and an outlet conduit 1 at its bottom. Mounted in the casing 5 are cooling coils 8. While only one vertically arranged cooling coil 8 is shown in the drawing, it will be understood that a series of such coils are arranged in side by side relationship and extend throughout substantially the entire length and width of the absorber. Each cooling coil 8 comprises a plurality of pipe'sections 9 arranged one overthe other in a vertical plane with the ends of adjacent pipe sections connected alternately at opposite ends by U- shaped couplings H] to provide a continuous coil, see Fig. 2. The cooling coils 8 are supported at their center and adjacent each end by stanchions in the form of plates 1 Cooling'water is supplied to the cooling coils 8 through a header l2 and supply pipe l3 from any suitable source such as a, city water main, coolingtower or the like. Cooling water from the bank of cooling coils 8 is delivered throu h a header l4 and conduit IE to a waste pipe or preferablytoa condenser, not shown.

Liquid absorbent'is supplied to the top oft he f absorber through a conduit I6 and is dispersed.

by a liquid divider I1 for gravity flow over the plurality of cooling coils 8. The liquid divider I! may be of any suitable form for delivering absorbent uniformly throughout the length of the uppermost pipe sections 8 of the cooling coils 8. With such a liquid divider ll, the absorbent liquid is supplied to the uppermost pipe section 9 of each cooling, coil 8-by a dripper plate l8-having a depending serrated edge 19 overlying the pipe section. Liquid is supplied to the dripper plate l8 from a longitudinal trough of the liquid divider H by a capillary cover plate 20 of the type illustrated and described in detail in said Edberg patent. Absorbent liquid dripsfrom-the lower serrated edge IQ of the plate I8 onto the top of the uppermost pipe sections 9 and flows by gravity over the surface of the pipe section and drips onto the next lowermost pipe section and thus flows by gravity from the top to the bottom of each cooling coil 8 to wet its entire surface area with absorbent. liquid.

In .accorditncewith the present invention wire. loops surroundeach pipe sectionloosel-yat inter.- vals along. .its.le'ngth to provide aspace between thelloops. and, the sides. and. bottom of. the pipe. Th'eloops. are preferably. formed. by. the turns it of a helically coiled wire .2.5.extendihg.between the.s tanchions...l l. Theendsloi the coiled-wires 25 may. be..,foi'med..paralleli with the stanchions- Il .butjpreferabl'y. they are merely, cut to length. so thattheir: ends ..engage thestanchions. at a single point', .see..Fig. 2." As. illustrated in detail in 3 and.'4' thecylinder. of each helically coiled. wirie '25flhas. .an. inside diameter slightly. greater, than the. outside. diameter of. the pipe sections!) to. provide. a space a between each turn; t of the coil and the sides and bottom of the pipe sections 9.. The sizeof the wire, the pitch between adjacent turns and the spacing'a depends upon the viscosity of absorbent solution. As one example, No. 14'wire'(B; & S. gauge)" havingj'a diameter of..064 oi an'inch and wound in-a helicalcoil25fon'a cylinder having aninside diameter of 5 of aniinch. withthe' individual-turns t. spaced apart [9; inch when mounted on Ipipe"sec-' tions ofgan inch iii-diameter have produced a verygood gliquid" distribution of a lithium bromide solution" throughout the surface area'of the-pipe sections 9. With "helically/coiled wires 25 -and' pipe sections 9 ofthe' dimensions indi-'- cated; a space a of f e-I01 an inch is provided 'be-' tween-thebottom of the pipe sections" and the inside'of-"the individual turnst of the coilsf The helically-coiled wires25ar'e 'relatively'im' expensive to manufacture and are adapted "to be" assembled on the pipe sections 9 of the-cooling" coils -8'-with facility. When'assemblin'g thecooling' coils 8 intoan integral structure one end of" thepipe sections -9 is'fir'st inserted through holes in-one-of'the supporting plates 1 l. A- helicallycoiledwire- 25 is then slid over the free end-of each pipe section 9. The intermediate-supportingplate I|is' placedin position onthe pipe sections 9 after-which another-'set'of the helically-coiled" wiresQSis slid overthe free ends of 'the pipe sec tions; The third plate H "ismounted in position" at the opposite ends of the pipe sectioiis'fiarid the pipes-are.- connectedto. the'sup'po'rtinJ plates or stanchions l!"as"by.tack welding or the'lilie to providea rigid structure. The u shaped. con- M, respectively, to adapt a cooling medium to be circulated therethrough. The liquid divider I1 is mounted on the top of the stanchions II as illustrated in Fig. 2 so that a dripper plate overlies the uppermost pipe section [3 of each individual cooling coil 8. The assembly of cooling coils 8 and liquid divider I1 is then inserted in the absorber shell- 5 and end-plates 26 applied to hermeticallyseal the absorber. One form of the invention having now been described in detail the mode of operation is explained as follows.

Liquid absorbent supplied through the conduit IG-is dispersed by the liquid divider H and delivered through the cover plates 20 onto the sides of the-dripper plates I8. Liquid absorbent drips from the lower serrated edge 19 of the dripper plate 18 to uniformly supply absorbent liquid throughout the length of the uppermost pipe section- 9 0i each cooling coil 8. The absorbent liquid flows by gravity over the surface of each pipe section 9 toward the bottom and drips onto the top" of the" next lowermost pi'pe' section. Thus the liquid absorbent "continuously drips from pipe" section to pipe section 8' from the top' to the bottom" of each cooling coil 8.

An absorbent liq'uid' supplied to "a particular por'tibiiof any pipe section" '9 is retained between, the turns t of 'the helically coiled wire 25' which limits the flow longitudinally ofthe' pipe'sections.

a wiping" action of the" liquid over the surfaced-'- the" p'ipese'ctior'i as 'it flows in a helical path' along the individual turns-1' toward the bottom of thepipe'; Alsd'the surface tenfsi'on'of the liq'uld abs'orbent'tendsto restrainits flowfroin' the space" section "onto" which they" fall without splashing or bouncing away from the surfaceof'the'pibe" section 'arid'fallin'g t the"bottomof'theabsorbrl pipe sections 9" provides --a large surface" area of I absorbent for absorbing refrigerant vapor"and* also for-transferring heat to" the cooling medium" circulating" throu'gli'the cooling coils a. Absorp-' tionsolution' flows" by gravity" from" the bottom: of the absorber" casing 5' through the conduit l.

absorber-orarr absorption refrigeration system? It will also "be 1 observed" that the present in've'n tionutilizesthe'surface tension oftlieliqu'idab sorbent "for producing "a desirable" wiping "actionofliq'ui'd over'th'e surfac'e' 'of" the pipe sections as it Tlows'in ahelical path following the'cont'our'of the turns of the helically coiled wire. lt wilistill" 0 furtherbe observed'thatthe'l o '11- 4 nectors Illthen may bewelded. to-the-ends of-ad o Sely tted coiled Wire's --als'o producefsmaller dropswhich avoid splashing or' liquidaway -frorrithesurface of pipesection's'.

While'a single embodiment of" the invention is: I

hereinillustratedand'describedyit will be'under-f stood that modifications may be made in the construction and arrangement of elements without departing from the spirit or scope of the invention. Therefore, without limitation in this respect, the invention is defined by the following claim.

I claim: 7

A heat transfer device having a plurality of pipe sections arranged one over the other in a vertical plane, means for flowing a fluid through the interior of the pipe sections, means for directing droplets of a liquid onto the exterior of the uppermost pipe section at spaced points along the top thereof which drips from the bottom of each pipe section onto the top of the next lowermost pipe section from the top to the bottom of the device, a helically wound wire surrounding each pipe section and resting on the top thereof with a space between the loops of the wire helix and the sides and bottom of the pipe section, each loop of the wire helix constituting a drip former from which liquid drips at spaced points from the 6 bottom of the pipe section, and the space between the loops of the wire helix and the pipe section being so related to the surface tension of the liquid as to cause the liquid to cling in the space and thereby interrupt the flow of liquid longitudinally of the pipe section and form small drops as liquid drips from each loop.

JOHN DAVIDSON,

REFERENCES CITED The following references are of record in'the file of this patent:

UNITED STATES PATENTS Number Name Date 347,552 Carlson Mar. 19, 1907 FOREIGN PATENTS Number Country Date 19,566 Switzerland June 21. 1899 414,720 France June 25, 1910 

